CPC · California Plumbing Code

How does the California Energy Code affect water heater installations?

If you replace or alter a water heater in California, CPC **§501.2** requires you to follow the California Energy Code options and installation details—choose an allowed system (gas, qualifying HPWH, or allowed electric), insulate pipes, install required controls/communication interfaces and demand recirculation where applicable, and obtain permits and inspections before final approval.

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Last reviewed: July 6, 2026

What the code requires — 2–4 sentences

The California Plumbing Code requires that water‑heater installations comply with the California Energy Code requirements referenced in §501.2 — i.e., altered or replacement service water‑heating systems must meet the CEC mandatory requirements (including pipe insulation, permissible system types, recirculation controls, and equipment features) and related CEC sections such as §110.3 and §150.0(n). §501.2 is the CPC gateway: it directs installers and permitting authorities to apply the Energy Code provisions to water‑heater work.

The single most important rule: when you replace or alter a water heater in California follow the Energy Code options and requirements that §501.2 adopts — pick an allowed system type and install required controls, insulation, and interfaces specified by the Energy Code.

Requirements in detail

Scope and starting points

  • The CPC §501.2 (the controlling section) adopts the California Energy Code requirements for service water‑heating systems and points to CEC §110.3 for mandatory equipment/installation requirements and CEC §150.0(n) for residential mandatory requirements. Compliance with those CEC provisions is required for altered or replacement systems under the CPC.

  • Permit and inspection obligations still apply under the CPC: obtain a permit before installing, removing, or replacing a water heater per §502.1, and complete final inspection/approval per §503.2.

Which system types are allowed for altered/replacement installations

The CEC (as adopted/referenced by §501.2) gives authorized choices for altered or replacement service water heaters. Key allowed options include:

  • A natural gas or propane water‑heating system.
  • A single Heat Pump Water Heater (HPWH) — with specific siting, pad, and communication/interface requirements.
  • A single HPWH meeting NEEA Advanced Water Heater Specification Tier 3 or higher.
  • If the existing unit is an electric resistance water heater, a consumer electric water heater may be allowed as an option.

These options are consolidated in the CPC §501.2 adoption of the Energy Code.

Mandatory installation features called out by the Energy Code (via §501.2)

  • Pipe insulation: newly installed and existing accessible piping must meet the Energy Code insulation rules (CEC pipe insulation sections referenced by §501.2).

  • Recirculation distribution systems: where a recirculation loop serves individual dwelling units, only demand recirculation systems with manual on/off control (as specified in Reference Appendix RA4.4.9) are permitted.

  • HPWH siting and pad: a single HPWH storage tank shall not be located outdoors and shall be placed on an incompressible, rigid, insulated surface with minimum thermal resistance R‑10. The HPWH must also have a communication interface that meets §110.12(a) or provide an ANSI/CTA‑2045‑B communication port where required.

  • Equipment communication & controls: certain HPWHs and systems must include the specified communication interface and meet CEC controls/backup‑heat/ventilation requirements for HPWH installations.

  • Size & capacity: the CPC still requires minimum capacity based on the First‑Hour Rating (Table 501.1(2)) for storage water heaters; solar systems must be sized to meet the same first‑hour rating.

Quick decision table (decision‑relevant dimensions / values)

Decision factor Requirement / value Code Reference
Allowed replacement system types Natural gas/propane OR single HPWH OR HPWH meeting NEEA Tier 3 OR (if existing is electric) consumer electric water heater §501.2 — ; CEC §150.1(c)8 —
Pipe insulation Newly installed and existing accessible piping must meet Energy Code insulation rules §501.2 referencing CEC (pipe insulation) — ;
Recirculation controls Only demand recirculation with manual on/off per RA4.4.9 for dwelling units §501.2 referencing RA4.4.9 — ;
HPWH pad & location Tank not located outdoors; placed on incompressible, rigid surface with R‑10 minimum CEC requirement adopted by §501.2 — ;
Communication interface HPWH must have interface meeting §110.12(a) or ANSI/CTA‑2045‑B port CEC requirement adopted by §501.2 — ;
Minimum capacity / sizing First‑Hour Rating per Table 501.1(2) (use table to size storage heaters) CPC Table 501.1(2) —

Documentation, permits, and inspections

  • A permit is required before installing, replacing or removing a water heater per §502.1; inspections (including vent/chimney inspection and a final water‑heater inspection) are required under §503.1 and §503.2. Final installation must be approved by the Authority Having Jurisdiction.

Exceptions & special cases

  • The Energy Code includes specific exceptions (for example, small new dwelling units under 500 ft² may accept point‑of‑use electric water heaters, and certain 120‑V HPWH allowances for very small units) — these exceptions are part of the CEC provisions that §501.2 adopts. Check the CEC exceptions cited by §501.2 for the exact applicability.

  • Factory‑precharged packaged systems may be excepted from some field verification tests under CEC exceptions; again, those exceptions are invoked through §501.2 where the CPC defers to the Energy Code.

  • For multifamily or central systems, the Energy Code imposes different (often stricter) requirements (e.g., central HPWH system controls, storage temperatures, separate recirculation‑loop tanks) — these distinctions are in the CEC passages adopted by §501.2 and must be followed for multi‑dwelling systems.

If you need to apply an exception, always confirm the exact CEC subsection referenced by §501.2 to verify the exception language.

Common mistakes

  • Assuming the CPC alone governs water‑heater replacements. In California, §501.2 requires following the Energy Code provisions — installers who ignore the CEC rules (pipe insulation, allowed system types, communication interfaces) are out of compliance.

  • Installing a HPWH outdoors or on an uninsulated/compressible pad (violates the R‑10 pad / indoor location requirement). Check the R‑10 pad and location requirement adopted via §501.2.

  • Using an existing recirculation loop that is not a permitted demand recirculation system with manual on/off control (CEC/RA4.4.9 requirement adopted by §501.2).

  • Omitting the required communication interface (CEC §110.12(a) or ANSI/CTA‑2045‑B) on HPWHs when the Energy Code requires it per §501.2.

  • Not obtaining permits or skipping final inspection; CPC §502.1 and §503.2 remain mandatory even when following the Energy Code.

Worked example — replacing a gas storage water heater with an HPWH

Scenario: Existing single‑family dwelling, 3 bedrooms / 2 bathrooms (typical), replacing an existing gas storage water heater with a single HPWH.

Step 1 — Sizing: Use CPC Table 501.1(2) to determine First‑Hour Rating. For a 3‑bedroom / 2‑bath unit the table shows 62 gallons first‑hour rating (install to at least that rating or equivalent performance).

Step 2 — System choice: Under §501.2 the Energy Code allows a single HPWH as an acceptable replacement option provided it meets the CEC requirements (or use a qualifying NEEA Tier 3 HPWH).

Step 3 — Siting & pad: The HPWH storage tank must not be located outdoors and must sit on an incompressible, rigid, insulated surface of at least R‑10. Verify the installation space can accommodate the HPWH per the CEC ventilation/space requirements if the HPWH needs room air.

Step 4 — Controls & interfaces: Install the required communication interface (CEC §110.12(a) or ANSI/CTA‑2045‑B) on the HPWH if the model or the CEC requires it for this application. Provide pipe insulation per the Energy Code. If there is a recirculation loop, convert it to a demand recirculation system with manual on/off control per RA4.4.9.

Step 5 — Permits & inspection: Pull a permit per §502.1 and schedule required inspections (vent, final) under §503.1/§503.2; obtain AHJ approval.

Bottom line for this example: a correctly sized HPWH (≥62 FHR), tank sited indoors on an R‑10 pad, with required communication interface, pipe insulation, and demand recirculation (if applicable), plus permits/inspections, will meet the combination of CPC §501.2 (which adopts CEC requirements) and the referenced Energy Code provisions.

Related provisions (CPC sections you’ll commonly use)

  • §501.1 — Applicability and general installation/sizing references (Table 501.1(2)).
  • §501.2 — California Energy Code water‑heating system requirements (controlling section).
  • §502.1 — Permits required for installation/replacement.
  • §503.1 / §503.2 — Inspection (chimneys/vents) and final water‑heater inspection.
  • §504.1 — Location requirements for water heaters (bedrooms/bathrooms and closet rules).
  • §504.2 / §504.3 — Vent and clearance requirements for water heaters.
  • §505.1 — Other fuel types and referenced standards for non‑gas water heaters.
  • CEC sections referenced by §501.2 you will need to consult directly for details: §110.3, §150.0(n), and the referenced Residential/Reference Appendices (RA).

Code references

Grounded in the retrieved California Plumbing Code — click a citation to read the verbatim passage:

  • CPC § 150.2 High relevance — show source text

    Exception to Section 150.2(b)1Fiii: Entirely new or complete replacement packaged systems for which the manufacturer has verified correct system refrigerant charge prior to shipment from the factory are not required to have refrigerant charge confirmed through field verification and diagnostic testing. The installer of these packaged systems shall certify on the Certificate of Installation that the packaged system was pre-charged at the factory and has not been altered in a way that would affect the charge. Ducted systems shall comply with minimum system airflow rate requirement in Section 150.2(b)1Fiiib, provided that the system is of a type that can be verified using the procedure specified in Section RA3.3 or an approved alternative in Section RA1. G. Altered space-heating system. Altered or replacement space-heating systems shall not use electric resistance as the primary heat source. Exception 1 to Section 150.2(b)1G: Nonducted electric resistance space heating systems, if the existing space heating system is electric resistance. Exception 2 to Section 150.2(b)1G: Ducted electric resistance space heating systems, if the existing space heating system is electric resistance and a ducted space cooling system is not being replaced or installed.

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    SINGLE-FAMILY RESIDENTIAL BUILDINGS—ADDITIONS AND ALTERATIONS TO EXISTING RESIDENTIAL BUILDINGS

    Exception 3 to Section 150.2(b)1G: Electric resistance space heating systems, if the existing space heating system is electric resistance and the building is located in Climate Zone 7 or 15. H. Water-heating system. Altered or replacement service water-heating systems or components shall meet the applicable requirements below: i. Pipe insulation. For newly installed and existing accessible piping, the insulation requirements of Section 150.0(j)1 shall be met. ii. Distribution system. For recirculation distribution systems: serving individual dwelling units, only demand recirculation systems with manual on/off control as specified in the Reference Appendix RA4.4.9 shall be installed. iii. Water heating system. The water heating system shall meet one of the following: a. A natural gas or propane water-heating system; or b. A single heat pump water heater. The storage tank shall not be located outdoors and be placed on an incompressible, rigid insulated surface with a minimum thermal resistance of R-10. The water heater shall be installed with a communication interface that either meets the requirements of Section 110.12(a) or has an ANSI/CTA-2045-B communication port; or c. A single heat pump water heater that meets the requirements of NEEA Advanced Water Heater Specification Tier 3 or higher; or d. If the existing water heater is an electric resistance water heater, a consumer electric water heater; or e. A water-heating system determined by the Executive Director to use no more energy than the one specified in Item a above; or if no natural gas is connected to the existing water heater location, a water-heating system determined by the executive director to use no more energy than the one specified in Item d above. I. Roofs. Replacements of the exterior surface of existing roofs, including adding a new surface layer on top of the existing exterior surface, shall meet the requirements of Section 110.8 and the applicable requirements of Subsections i and ii where more than 50 percent of the roof is being replaced. i. **Steep-sloped roofs.

  • CPC § 501.1 High relevance — show source text

    Table 501.1(1) Water Heaters . . . . . . . . . . . . . . . .83

    501.2 California Energy Code Water Heating System Requirements . . . . . . . . . . . . . . . . .83

    502.0 Permits . . . . . . . . . . . . . . . . . . . . . .83

    502.1 General . . . . . . . . . . . . . . . . . . . . . .83

    503.0 Inspection . . . . . . . . . . . . . . . . . . . .83

    503.1 Inspection of Chimneys or Vents . . .83

    503.2 Final Water Heater Inspection . . . .83

    504.0 Water Heater Requirements . . . . . .83

    504.1 Location . . . . . . . . . . . . . . . . . . . . .83

    Table 501.1(2) First Hour Rating . . . . . . . . . . . . . .83

    504.2 Vent . . . . . . . . . . . . . . . . . . . . . . . .84

    504.3 Clearance . . . . . . . . . . . . . . . . . . . .84

    504.4 Pressure-Limiting Devices . . . . . . .84

    504.5 Temperature-Limiting Devices . . . .84

    504.6 Temperature, Pressure, and Vacuum Relief Devices . . . . . . . . .84

    504.7 Lead Content . . . . . . . . . . . . . . . . .84

    505.0 Oil-Burning and Other Water Heaters . . . . . . . . . . . . . . . . . . . . . .84

    505.1 Water Heaters . . . . . . . . . . . . . . . .84

    505.2 Safety Devices . . . . . . . . . . . . . . . .84

    505.3 Oil-Fired Water Heaters . . . . . . . . .84

    505.4 Indirect-Fired Water Heaters . . . . .84

    506.0 Air for Combustion and

    Ventilation . . . . . . . . . . . . . . . . . . . .84

    506.1 General . . . . . . . . . . . . . . . . . . . . . .84

    506.2 Indoor Combustion Air . . . . . . . . . .85

    506.3 Indoor Opening Size and Location . . . . . . . . . . . . . . . . . . . . .85

    506.4 Outdoor Combustion Air . . . . . . . . .85

    506.5 Combination Indoor and

    Outdoor Combustion Air . . . . . . . . .87

    506.6 Engineered Installations . . . . . . . . .87

    506.7 Mechanical Combustion Air Supply . . . . . . . . . . . . . . . . . . . . . . .87

    506.8 Louvers, Grilles, and Screens . . . .87

    506.9 Combustion Air Ducts . . . . . . . . . . .87

    507.0 Appliance and Equipment Installation Requirements . . . . . . . .88

    507.1 Dielectric Insulator . . . . . . . . . . . . .88

  • CPC § 0.293 High relevance — show source text

    For SI units: 1000 British thermal units per hour = 0.293 kW

    • Dual purpose water heaters shall be installed in accordance with this code and the manufacturer’s installation instructions.

    501.2 California Energy Code Water Heating System Requirements. [CEC] See California Energy Code Section 110.3 for additional mandatory requirements for all service water heating systems, and 150.0(n) for additional mandatory requirements for residential service water heating systems.

    502.0 Permits.

    502.1 General. It shall be unlawful for a person to install, remove, or replace or cause to be installed, removed, or replaced a water heater without first obtaining a permit from the Authority Having Jurisdiction to do so.

    TABLE 501.1(1)

    WATER HEATERS

    For SI units: 1000 British thermal units per hour = 0.293 kW

    • Dual purpose water heaters shall be installed in accordance with this code and the manufacturer’s installation instructions.

    503.0 Inspection.

    503.1 Inspection of Chimneys or Vents. This inspection shall be made after chimneys, vents, or parts thereof, authorized by the permit, have been installed and before such vent or part thereof has been covered or concealed.

    503.2 Final Water Heater Inspection. This inspection shall be made after work authorized by the permit has been installed. The Authority Having Jurisdiction will make such inspection as deemed necessary to be assured that the work has been installed in accordance with the intent of this code.

    No appliance or part thereof shall be covered or concealed until the same has been inspected and approved by the Authority Having Jurisdiction.

    504.0 Water Heater Requirements.

    504.1 Location. Water heater installations in bedrooms and

    bathrooms shall comply with one of the following [NFPA 54:10.27.1]:

    (1) Water heater shall be of the direct-vent type. [NFPA 54:10.27.1(2)]

    (2) Fuel-burning water heaters shall be permitted to be installed in a closet located in the bedroom or bathroom provided the closet is equipped with a listed, gasketed door assembly and a listed self-closing device. The selfclosing door assembly shall meet the requirements of Section 504.1.1. The door assembly shall be installed with a threshold and bottom door seal and shall meet the requirements of Section 504.1.2. Combustion air for such installations shall be obtained from the outdoors in accor dance with Section 506.4. The closet shall be for the

    exclusive use of the water heater.

    504.1.1 Self-Closing Doors. Self-closing doors shall swing easily and freely, and shall be equipped with a self-closing device to cause the door to close and latch each time it is opened. The closing mechanism shall not have a hold-open feature.

    504.1.2 Gasketing. Gasketing on gasketed doors or frames shall be furnished in accordance with the published listings of the door, frame, or gasketing material manufacturer.

    TABLE 501.1(2) FIRST HOUR RATING [1]

  • CPC § 507.2 High relevance — show source text

    2_
    507.2|||X|X|X|||X|||||||||||||||||

    This state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.0.

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    ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

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    ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

    CHAPTER 5

    WATER HEATERS

    501.0 General.

    501.1 Applicability. The regulations of this chapter shall govern the construction, location, and installation of fuel-burning and other types of water heaters heating potable water, together with chimneys, vents, and their connectors. The minimum capacity for storage water heaters shall be in accordance with the first-hour rating listed in Table 501.1(2). A list of accepted water heater appliance standards is referenced in Table 501.1(1). Listed appliances shall be installed in accordance with the manufacturer’s installation instructions. Unlisted water heaters shall be permitted in accordance with Section 504.3.2.

    Water heaters shall be installed in accordance with the

    manufacturer’s installation instructions. The final installation shall be approved by the Authority Having Jurisdiction.

    TABLE 501.1(1)

    WATER HEATERS

    TYPE* STANDARD


    Electric, Household Storage    		 UL 174


    Oil-Fired Storage Tank    		 UL 732


    Gas-Fired, 75 000 Btu/h or less,
    Storage    		 CSA/ANSI Z21.10.1/CSA 4.1


    Gas-Fired, Above 75 000 Btu/h,
    Storage and Instantaneous    		 CSA/ANSI Z21.10.3/CSA 4.3

    Electric, Commercial Storage    		 UL 1453
    Solid Fuel-Fired UL 2523


    Electric Instantaneous    		 UL 499

    For SI units: 1000 British thermal units per hour = 0.293 kW

    • Dual purpose water heaters shall be installed in accordance with this code and the manufacturer’s installation instructions.

    501.2 California Energy Code Water Heating System Requirements. [CEC] See California Energy Code Section 110.3 for additional mandatory requirements for all service water heating systems, and 150.0(n) for additional mandatory requirements for residential service water heating systems.

    502.0 Permits.

    502.1 General. It shall be unlawful for a person to install, remove, or replace or cause to be installed, removed, or replaced a water heater without first obtaining a permit from the Authority Having Jurisdiction to do so.

    TABLE 501.1(1)

    WATER HEATERS

    For SI units: 1000 British thermal units per hour = 0.293 kW

    • Dual purpose water heaters shall be installed in accordance with this code and the manufacturer’s installation instructions.

    503.0 Inspection.

  • CPC § 150.1 High relevance — show source text

    Exception 1 to Section 150.1(c)7A: Packaged systems for which the manufacturer has verified correct system refrigerant charge prior to shipment from the factory are not required to have refrigerant charge confirmed through field verification and diagnostic testing. The installer of these packaged systems shall certify on the Certificate of Installation that the packaged system was pre-charged at the factory and has not been altered in a way that would affect the charge. Ducted systems shall comply with minimum system airflow rate requirements in Section 150.1(c)7Aib, provided that the system is of a type that can be verified using the procedure specified in Section RA3.3 or an approved alternative in Section RA1.

    1. Domestic water-heating systems. Water-heating systems shall meet the requirements of A, B or C, or shall meet the performance compliance requirements of Section 150.1(b)1. For recirculation distribution systems, only demand recirculation systems with manual on/off control as specified in the Reference Appendix RA4.4.9 shall be used: A. A single 240 volt heat pump water heater (HPWH). The storage tank shall be located in the garage or conditioned space. In addition, meet the following: i. A compact hot water distribution system that is field verified as specified in the Reference Appendix RA4.4.6 in Climate Zones 1 and 16; and

    ii. A drain water heat recovery system that is field verified as specified in the Reference Appendix RA3.6.9 in Climate Zone 16.

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    SINGLE-FAMILY RESIDENTIAL BUILDINGS—PERFORMANCE AND PRESCRIPTIVE COMPLIANCE APPROACHES

    B. A single 240 volt HPWH that meets the requirements of NEEA Advanced Water Heater Specification Tier 3 or higher. In addition, for Climate Zone 16, a drain water heat recovery system that is field verified as specified in Reference Appendix RA3.6.9 and the storage tank shall be located in the garage or conditioned space. C. A solar water-heating system with electric backup meeting the installation criteria specified in Reference Residential Appendix RA4 and with a minimum annual solar savings fraction of 0.7. Exception 1 to Section 150.1(c)8: An electric water heater with point of use distribution as specified in RA4.4.5 may be installed for new dwelling units with a conditioned floor area of 500 square feet or less. Exception 2 to Section 150.1(c)8A and B: A 120V HPWH may be installed in place of a 240V HPWH for new dwelling unit with one bedroom or fewer.

    1. Space-conditioning distribution systems. All space-conditioning systems shall meet all applicable requirements of A or B below:

    A. High performance attics. Air handlers or ducts are allowed to be in ventilated attic spaces when the roof and ceiling insulation level meet Option B in Table 150.1-A. Duct insulation levels shall meet the requirements in Table 150.1-A. B. Duct systems and air handlers of HVAC systems shall be located entirely in conditioned space and confirmed through field verification and diagnostic testing to meet the criterion of Reference Residential Appendix Section RA3.1.4.3.8. Duct insulation levels shall meet the requirements in Table 150.1-A. For dwelling units with attics, the duct system and air handlers of HVAC systems shall be located below the ceiling separating the occupiable space from the attic.

  • CPC § 110.3 High relevance — show source text

    For HPWH installations with ducts, the following requirements shall be met: a. The space joined to the installation space via ducts shall meet the minimum volume of Section 110.3(c)7B2 above, minus the volume of the HPWH installation space; and b. All duct connections and building penetrations shall be sealed; and c. Exhaust air ducts and all ducts which cross pressure boundaries shall be insulated to minimum of R-6; and

    d. Where only the HPWH inlet or outlet is ducted, installation space shall include permanent openings that consist of a single layer of fixed flat slat louvers or grilles in the bottom half of the room, and/or a door undercut. With a ducted inlet, the minimum NFA shall be equal to the cross-sectional area of the duct. With a ducted exhaust, the minimum NFA shall be the larger of 20 square inches or the minimum NFA provided by the manufacturer for this method; and e. Where the inlet and outlet ducts both terminate within the same pressure boundary, airflow from the termination points shall be diverted away from each other. Note: Ducting only the inlet or the exhaust across the pressure boundary could interfere with balanced ventilation systems. This should be considered when specifying HPWH location and ventilation method.

    Note: Authority: Sections 25213, 25218, 25218.5, 25402 and 25402.1, Public Resources Code . Reference: Sections 25007, 25008, 25218.5, 25310, 25402, 25402.1, 25402.4, 25402.8, and 25943, Public Resources Code.

    SECTION 110.4—MANDATORY REQUIREMENTS FOR POOL AND SPA SYSTEMS AND EQUIPMENT

    (a) Certification by manufacturers. Any pool theater for a pool, spa, or a pool and spa combination shall be installed only if the manufacturer has certified that the system or equipment has all of the following:

    1. Efficiency. Equipment subject to State or federal appliance efficiency standards shall comply with the applicable provisions of Section 110.1; and

    2. On-off switch. A readily accessible on-off switch, mounted on the outside of the heater that allows shutting off the heater without adjusting the thermostat setting; and

    3. Instructions. A permanent, easily readable and weatherproof plate or card that provides the energy efficiency rating and instruction for the energy efficient operation of the pool and/or spa heater; and

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    ALL OCCUPANCIES—MANDATORY REQUIREMENTS FOR THE MANUFACTURE, CONSTRUCTION AND INSTALLATION OF SYSTEMS, EQUIPMENT AND BUILDING COMPONENTS

    (b) Installation. Any pool and/or spa system or equipment shall meet the following requirements:

    1. Heating equipment. Equipment installed to heat water for pools and/or spas shall be selected from equipment meeting the standards shown in Table 110.4-A.
  • CPC § 608.3. Medium relevance — show source text

    A water heating recirculation loop shall meet the following requirements: A. Air release valve or vertical pump installation. An automatic air release valve shall be installed on the recirculation loop piping on the inlet side of the recirculation pump and no more than 4 feet from the pump. This valve shall be mounted on top of a vertical riser at least 12 inches in length and shall be accessible for replacement and repair. Alternatively, the pump shall be installed on a vertical section of the return line. B. Recirculation loop backflow prevention. A check valve or similar device shall be located between the recirculation pump and the water heating equipment to prevent water from flowing backwards though the recirculation loop. C. Equipment for pump priming. A hose bibb shall be installed between the pump and the water heating equipment. An isolation valve shall be installed between the hose bibb and the water heating equipment. This hose bibb is used for bleeding air out of the pump after pump replacement. D. Pump isolation valves. Isolation valves shall be installed on both sides of the pump. These valves may be part of the flange that attaches the pump to the pipe. One of the isolation valves may be the same isolation valve as in Item C. E. Cold water supply and recirculation loop connection to hot water storage tank. Storage water heaters and boilers shall be plumbed in accordance with the manufacturer’s specifications The cold water piping and the recirculation loop piping shall not be connected to the hot water storage tank drain port. F. Cold water supply backflow prevention. A check valve shall be installed on the cold water supply line between the hot water system and the next closest tee on the cold water supply line. The system shall comply with the expansion tank requirements as described in the California Plumbing Code Section 608.3.

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    ALL OCCUPANCIES—MANDATORY REQUIREMENTS FOR THE MANUFACTURE, CONSTRUCTION AND INSTALLATION OF SYSTEMS, EQUIPMENT AND BUILDING COMPONENTS

    1. Service water heaters in state buildings. Any newly constructed building constructed by the State shall derive its service water heating from a system that provides at least 60 percent of the energy needed for service water heating from site solar energy or recovered energy, per the statutory requirement of California Public Resources Code Section 25498.

    Exception to Section 110.3(c)5: Buildings for which the state architect determines that service water heating from site solar energy or recovered energy is economically or physically infeasible. 6. Isolation valves. Instantaneous water heaters with an input rating greater than 6.8 kBTU/hr (2 kW) shall have isolation valves on both the cold water supply and the hot water pipe leaving the water heater, and hose bibbs or other fittings on each valve for flushing the water heater when the valves are closed. 7. Air-source heat pump water heaters (HPWH). HPWH shall meet the following requirements: A. Backup heat. Backup heat is required for systems where inlet air is unconditioned, unless the compressor cut-off temperature is below the Heating Winter Median of Extremes for the closest location listed in Table 2-3 from Reference Joint Appendix JA2. Backup heat may be internal or external to the HPWH. B. Ventilation. Consumer integrated HPWHs shall meet one of the ventilation requirements below.

  • CPC § 1305.2.3.3 Medium relevance — show source text

    2, 1305.2.3.3, 1305.2.4.1, 1305.2.5, 1305.2.5.1, 1305.2.6, 1305.2.7.1, 1305.2.8, 1305.2.9, 1305.2.9.1, 1305.2.10, 1305.2.10.1, 1305.2.11, 1305.2.11.1, 1305.2.12.1, 1305.2.13, Table 1305.2.15, 1305.2.15.1, 1305.2.16.1, 1305.2.17, 1305.2.17.1, 1305.2.18, 1305.2.18.1, 1305.2.19, Table 1305.2.19, 1305.2.20, 1305.2.20.1, 1307.1.1, 1401.2, 1402.1, 1402.2, 1402.2.1, 1402.3, 1402.4, 1402.5, 1402.6, 1501.5, 1504.1.1, 1504.1.4.1, 1504.1.7, 1509.1, 1509.3, 1510.1

    CEC — 25 : California Energy Code

    302.2, 702.7, 708.1, 809.1, 907.1, 1104.1

    CFC—25: California Fire Code

    101.2.2, 101.4.2, 301.3.1, 302.2, 307.1, 308.1, 802.2.1, 802.2.3, 803.2.3, 803.4.1.1, 803.4.1.2, 803.4.1.3, 803.4.1.4, 803.4.1.5, 803.4.1.6, Table 804.5.1.1(1), 904.1.5, 1011.6.1.1, 1303.1.2, 1305.2.8.1, 1305.2.14, 1305.2.14.1, 1401.2, 1501.1, 1501.5, 1502.1, 1502.1.1, 1502.2, 1502.3, 1504.1, 1507.1, 1507.2

    CMC—25: California Mechanical Code

    302.2, 702.7, 807.1, 902.1.1, 1008.1, 1305.2.7.1, 1305.2.8, 1305.2.8.1

    CPC—25: California Plumbing Code

    302.2, 408.1, 702.7, 1009.1, 1009.2, 1009.3, 1009.5, 1302.1.6, 1503.1

  • CPC § 422.1 Medium relevance — show source text

    422.1 Fixture Count . . . . . . . . . . . . . . . . .67

    422.2 Separate Facilities . . . . . . . . . . . . .68

    422.3 Fixture Requirements for Special Occupancies . . . . . . . . . . .68

    422.4 Toilet Facilities Serving Employees and Customers . . . . . .68

    422.5 Toilet Facilities for Workers . . . . . .69

    422.6 Water Closet Compartment . . . . . .69

    422.7 Urinal Partitions . . . . . . . . . . . . . . .69

    422.8 Cosmetology . . . . . . . . . . . . . . . . .69

    422.9 Cosmetology Establishments . . . . .69

    422.10 Commissaries Serving Mobile Food Preparation Units . . . . . . . . .69

    422.11 Employee Lavatories in Food Establishments . . . . . . . . . . .69

    Table 422.1 Minimum Plumbing Facilities . . . . .70

    Table 4-1 Occupant Load Factor

    [BSC and DSA-SS] . . . . . . . . . . . .75

    Table 4-2 Minimum Plumbing Facilities

    [OSHPD 1, 2, 3, 4 & 5] . . . . . . . . .76

    CHAPTER 5 WATER HEATERS . . . . . . . . . . . .81

    501.0 General . . . . . . . . . . . . . . . . . . . . . .83

    501.1 Applicability . . . . . . . . . . . . . . . . . . .83

    Table 501.1(1) Water Heaters . . . . . . . . . . . . . . . .83

    501.2 California Energy Code Water Heating System Requirements . . . . . . . . . . . . . . . . .83

    502.0 Permits . . . . . . . . . . . . . . . . . . . . . .83

    502.1 General . . . . . . . . . . . . . . . . . . . . . .83

    503.0 Inspection . . . . . . . . . . . . . . . . . . . .83

    503.1 Inspection of Chimneys or Vents . . .83

    503.2 Final Water Heater Inspection . . . .83

    504.0 Water Heater Requirements . . . . . .83

    504.1 Location . . . . . . . . . . . . . . . . . . . . .83

    Table 501.1(2) First Hour Rating . . . . . . . . . . . . . .83

    504.2 Vent . . . . . . . . . . . . . . . . . . . . . . . .84

    504.3 Clearance . . . . . . . . . . . . . . . . . . . .84

    504.4 Pressure-Limiting Devices . . . . . . .84

    504.5 Temperature-Limiting Devices . . . .84

    504.6 Temperature, Pressure, and Vacuum Relief Devices . . . . . . . . .84

    504.7 Lead Content . . . . . . . . . . . . . . . . .84

  • CPC § 180.2 Medium relevance — show source text

    Existing duct systems constructed, insulated or sealed with asbestos are not required to comply with the requirements of Subsection 180.2(b)2Biiib.

    2025 CALIFORNIA ENERGY CODE 279

    on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

    MULTIFAMILY BUILDINGS—ADDITIONS, ALTERATIONS AND REPAIRS TO EXISTING MULTIFAMILY BUILDINGS

    1. Hot water systems . Altered or replacement water-heating systems or components serving individual dwelling units shall meet the applicable requirements below: A. Pipe insulation. For newly installed piping and existing accessible piping, the insulation requirements of Section 160.4(e) shall be met. B. Distribution system. For recirculation distribution system serving individual dwelling units, only demand recirculation systems with manual on/off control as specified in Reference Appendix RA4.4.9 shall be installed. C. Water-heating system. The water-heating system shall meet one of the following: i. A natural gas or propane water-heating system; or ii. A single heat pump water heater. The storage tank shall not be located outdoors and shall be placed on an incompressible, rigid insulated surface with a minimum thermal resistance of R-10. The water heater shall be installed with a communication interface that either meets the requirements of Section 110.12(a) or has an ANSI/CTA-2045-B communication port; or iii. A single heat pump water heater that meets the requirements of NEEA Advanced Water Heater Specification Tier 3 or higher; or iv. If the existing water heater is an electric resistance water heater, a consumer electric water heater. v. A water-heating system determined by the Executive Director to use no more energy than the one specified in Sections 180.2(b)3Ci through iii above; or if no natural gas is connected to the existing water heater location, a water-heating system determined by the Executive Director to use no more energy than the one specified in Section 180.2(b)3Civ above.

    2. Lighting. A. Dwelling unit lighting. The altered lighting system shall meet the lighting requirements of Section 160.5(a). The altered luminaires shall meet the luminaire efficacy requirements of Section 160.5(a). Where existing screw base sockets are present in ceiling-recessed luminaires, removal of these sockets is not required, provided that new JA8 compliant trim kits or lamps designed for use with recessed downlights or luminaires are installed. B. Common use area—lighting, sign lighting, and electrical power distribution systems . i. Spaces with lighting systems installed for the first time shall meet the applicable requirements of Sections 110.9, 160.5(b)1, 160.5(b)2, 160.5(b)3, 160.5(b)4, 160.5(c), 160.5(e), 170.2(b), and 170.2(e)1 through 170.2(e)6. ii. When the requirements of Section 160.5(b)4D are triggered by the addition of skylights to an existing building and the lighting system is not recircuited, the daylighting control need not meet the multi-level requirements in Section 160.5(b)4D. iii. New internally and externally illuminated signs shall meet the requirements of Sections 110.9, 160.5(d) and 170.2(e)7. iv. Altered indoor lighting systems.

  • CPC § 140.4 Medium relevance — show source text

    MULTI-PASS WATER HEATER is a water heater that the cold water passes through multiple times. The water temperature increases with each pass until the storage tank reaches the intended storage temperature.

    SINGLE-PASS WATER HEATER is a water heater which the cold water passes through once and is heated to the intended use temperature.

    2025 CALIFORNIA ENERGY CODE 35

    on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

    ALL OCCUPANCIES—GENERAL PROVISIONS

    WEST-FACING (See “orientation.”)

    WINDOW FILM is a fenestration attachment product that consists of a flexible adhesive-backed polymer film, which may be applied to the interior or exterior surface of an existing glazing system.

    WOOD HEATER is an enclosed wood-burning appliance used for space heating and/or domestic water heating.

    WOOD STOVE (See “wood heater.”)

    ZONAL describes characterized by or relating to a zone or zones.

    ZONE, CRITICAL is a zone serving a process where reset of the zone temperature setpoint during a demand shed event might disrupt the process, including but not limited to computer rooms, data centers, telecom and private branch exchange (PBX) rooms, and laboratories.

    ZONE, NONCRITICAL is a zone that is not a critical zone.

    ZONE, SPACE-CONDITIONING, is a space or group of spaces within a building with sufficiently similar comfort conditioning requirements so that comfort conditions, as specified in Section 140.4(b)3 or 150.0(h), as applicable, can be maintained throughout the zone by a single controlling device.

    SECTION 100.2—CALCULATION OF ENERGY BUDGETS

    Energy budgets are adopted by the Commission to establish the maximum energy consumption that a proposed building, or portion of a building, can be designed to consume. A building complies with the performance standards compliance approach if the energy consumption calculated for the proposed design building is no greater than the energy budget calculated for the standard design building using Commission-certified compliance software as specified by the Alternative Calculation Methods Reference Manual. The energy budget for newly constructed single-family, multifamily, and nonresidential buildings are expressed in terms of Long-Term System Cost (LSC) and Source Energy. The energy budget for additions and alterations for all building types are expressed in terms of LSC.

    Long-term System Cost (LSC) is calculated by multiplying for each hour of the year the site energy use (electricity kWh, natural gas therms, or fuel oil or LPG gallons) for each energy type by the applicable CEC-published LSC hourly factors. LSC hourly factors vary for each hour of the year and by energy type (electricity, natural gas, or propane), by Climate Zone and by building type (residential, nonresidential). LSC hourly factors are summarized in Reference Joint Appendix JA3. LSC hourly factors for propane are used for all energy obtained from depletable sources other than electricity and natural gas.

    Source Energy is calculated by multiplying for each hour of the year the site energy use (electricity kWh, natural gas therms, or fuel oil or LPG gallons) by Btu factors for fossil fuel consumed either directly at the building site or caused to be consumed to meet the electrical demand of the building considering the long-term marginal hourly resources of Commission-projected electric system resource procurement.

  • CPC § 608.3. Medium relevance — show source text

    The system shall comply with the expansion tank requirements as described in the California Plumbing Code Section 608.3.

    52 2025 CALIFORNIA ENERGY CODE

    on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

    ALL OCCUPANCIES—MANDATORY REQUIREMENTS FOR THE MANUFACTURE, CONSTRUCTION AND INSTALLATION OF SYSTEMS, EQUIPMENT AND BUILDING COMPONENTS

    1. Service water heaters in state buildings. Any newly constructed building constructed by the State shall derive its service water heating from a system that provides at least 60 percent of the energy needed for service water heating from site solar energy or recovered energy, per the statutory requirement of California Public Resources Code Section 25498.

    Exception to Section 110.3(c)5: Buildings for which the state architect determines that service water heating from site solar energy or recovered energy is economically or physically infeasible. 6. Isolation valves. Instantaneous water heaters with an input rating greater than 6.8 kBTU/hr (2 kW) shall have isolation valves on both the cold water supply and the hot water pipe leaving the water heater, and hose bibbs or other fittings on each valve for flushing the water heater when the valves are closed. 7. Air-source heat pump water heaters (HPWH). HPWH shall meet the following requirements: A. Backup heat. Backup heat is required for systems where inlet air is unconditioned, unless the compressor cut-off temperature is below the Heating Winter Median of Extremes for the closest location listed in Table 2-3 from Reference Joint Appendix JA2. Backup heat may be internal or external to the HPWH. B. Ventilation. Consumer integrated HPWHs shall meet one of the ventilation requirements below. Minimum volume and opening size requirements shall be the sum of all HPWHs installed within the same space. Compressor capacity shall be determined using AHRI 540 Table 4 reference conditions for refrigeration with the “High” rating test point: i. Installed using a method provided by the manufacturer to meet or exceed the level of performance provided by the ventilation requirements of Section 110.3(c)7B2 through Section 110.3(c)B4. ii. For HPWH installation without ducts, the installation space shall have a volume not less than the greater of 100 cubic feet per kBtu per hour of compressor capacity, or the minimum volume provided by the manufacturer for this method; or

    iii. For HPWH installation without ducts, the installation space shall be vented to a communicating space via permanent openings, according to the following requirements: a. Communicating space shall meet the minimum volume of Ssection 110.3(c)7B2 above, minus the volume of the HPWH installation space; and b. Permanent openings shall consist of a single layer of fixed flat slat louvers or grilles, with a total minimum Net Free Area (NFA) the larger of 125 square inches plus 25 square inches per kBtu per hour of compressor capacity, or the minimum provided by the manufacturer for this method. The permanent openings shall be fully louvered doors or two openings of equal area, one in the upper half of the enclosure and one in the bottom half of the enclosure. The top of the upper opening must be 12 inches or less from the enclosure top and the bottom of the lower vent must be 12 inches or less from the enclosure bottom; or iv.

Frequently asked questions

What is the single controlling CPC section that brings Energy Code rules into water‑heater work?

The controlling CPC provision is §501.2 — it adopts the California Energy Code requirements for water‑heating systems and points to CEC sections such as §110.3 and §150.0(n).

Do I still need a permit and final inspection if I install an eligible HPWH under the Energy Code?

Yes. The CPC requires a permit before installation (§502.1) and a final inspection/approval by the Authority Having Jurisdiction (§503.2), even when Energy Code options are followed.

Can I replace a gas water heater with a 240‑V HPWH outdoors?

No — for altered/replacement installations the Energy Code (adopted via §501.2) requires the HPWH storage tank not be located outdoors and to be placed on a rigid, incompressible, insulated surface with at least R‑10 thermal resistance.

If my house already has a hot‑water recirculation loop, what changes may be required?

For dwelling units the Energy Code (as adopted by §501.2) limits recirculation distribution systems to demand recirculation systems with manual on/off control per Reference Appendix RA4.4.9 — you may need to modify controls or equipment to comply.

Where do I find the required first‑hour rating to size a storage water heater?

Use CPC Table 501.1(2) (First‑Hour Rating) for minimum capacity requirements; solar systems must be sized to meet the same table values.

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